Interesting problem when restoring a public variable's lost value

[ACommandLineKindaGuy]

I have a number of public variables.

Option Private Module
Public Y, TF, SysAccess, RowsHidden, ColsHidden, PrintNotesAlso, DisplayNotesAlso, LastSelectionAllowEdit As Boolean

Some set the state of a custom control on a ribbon, EG

Sub getPressedRow(control As IRibbonControl, ByRef pressed)
'This sets the checkbox status on startup since by default checkboxes are unchecked
pressed = RowsHidden
End Sub

I then store the variable's value in a RowsHidden named range.

All good. Now, for some reason, there are occasions where the variable loses its value
So I have created the following sub as a temporary measure to find the problem

Sub CheckIfPublicVariableLostValue()    'Called from:
                                      'SystemAccess
                                      'Worksheet_SelectionChange on Proposal, Schedule, and Scratch sheets
'Sometime these variables get cleared when maintaining/troubleshooting workbook
With Worksheets("Proposal")
    If IsEmpty(SysAccess) Then MsgBox "SysAccess variable lost value"

    If IsEmpty(SysAccess) Then SysAccess = .Range("InSysAccess")
    If IsEmpty(RowsHidden) Then RowsHidden = .Range("RowsHidden")
    If IsEmpty(ColsHidden) Then ColsHidden = .Range("ColumnsHidden")
    If IsEmpty(PrintNotesAlso) Then PrintNotesAlso = .Range("PrintNotes")
    If IsEmpty(DisplayNotesAlso) Then DisplayNotesAlso = .Range("DisplayNotes")
End With
End Sub

When I see the message, I'm prepared to know that the code triggers an error, which I now have forgotten and of course cannot replicate but I do know that when I hover over the variable,the tooltip returns "Empty"

First Question: How do I fix this error?
2nd Question: Can my little sub be optimized to run faster?
TIA John

 

[ACommandLineKindaGuy]

The error code is 1004

 

[Micron]

No concrete idea why your variables lose their values but can say you should always indicate which line raises the error. 1004 is about the most useless number, given that it must represent about 8 or more different messages that you can get. One thing that you may not know is that in that line, all variables are variants except for LastSelectionAllowEdit. Perhaps this raises an error and your code disables error handling (e.g. by using Resume Next) and you don't know it. Errors often cause variables to lose their value and/or go out of scope. You should always explicitly declare every variable.